Enterococcus faecalis has often been isolated from asymptomatic and persistant root canal infections, chronic apical periodontitis and failed endodontic cases. It can survive in dentinal tubules for up to 10 days without nutrient supply. Serine protease and Ace aid in the adhesion of Enterococcus faecalis with dentin.
Calcium hydroxide has widely been accepted and used as a dental intracanal medicament because of its antimicrobial properties and its action on gram negative bacteria. It releases hydroxyl ions that are responsible for the creation of high alkalinity which has a destructive effect on bacterial cytoplasmic membrane and protein structure. The cytoplasmic membrane in most organisms is similar, irrespective of morphologic, tinctorial and respiratory characteristics of the organism. This means that calcium hydroxide will have similar effects on aerobic, anaerobic, gram positive and gram negative organisms. A pH of 10.5-11 delays the growth of Enterococcus faecalis, while a pH of 11 or more is known to eliminate Enterococcus faecalis. However, Enterococcus faecalis contains a proton pump that carries protons to the interior of the cell, acidifying its cytoplasm in situations of increased alkalinity in its environment. Thus, Enterococcus faecalis has been found to be resistant to most intracanal medicaments containing calcium hydroxide.
Linezolid is a synthetic antibiotic of the oxazolidinone group. It has been shown to be effective only on gram positive organisms. It inhibits protein synthesis in micro-organisms by disrupting the translation of messenger RNA (mRNA) into proteins in the ribosome. Linezolid acts during the initiation of protein synthesis by binding to the 23S portion of the 50S subunit (the centre of peptidyl transferase activity), preventing the formation of 70S ribosome complex that is responsible for the formation of the ‘initiation complex’ (composed of 30S and 50S subunits of the ribosomes, tRNA and mRNA).
Linezolid has been medically used for the treatment of skin and soft tissue infections, diabetic foot infections, pneumonia, infective endocarditis, tuberculosis, neutropenia, endophthalmos, meningitis, bone and joint infections including chronic osteomylitis. It has also shown to be effective against certain organisms which are also found inside root canals of teeth like: Staphylococccus aureus, Streptococcus agalactiae, Streptococcus pneumonia, Streptococcus pyogens, Streptococcus viridans group, Listeria monocytogenes and Corynebacterium. Linezolid is also effective against organisms responsible for resistant root canal infections like Enterococcus faecalis, Vancomycin-resistant Enterococcus faecalis and Vancomycin-resistant Enterococci.
The present inventors have meticulously carried out earnest work and devised a dental root canal filling composition that is very effective resistant root canal infections caused by Enterococcus faecalis and Vancomycin-resistant Enterococci.